From 8dbd406ea0f495b3d404a7433a32b4781953e55a Mon Sep 17 00:00:00 2001
From: Campbell Barton <ideasman42@gmail.com>
Date: Thu, 16 Dec 2021 16:17:28 +1100
Subject: WM: various changes to file writing behavior

Saving with only a filename (from Python) wasn't being prevented,
while it would successfully write the file to the working-directory,
path remapping and setting relative paths wouldn't work afterwards
as `Main.filepath` would have no directory component.

Disallow this since it's a corner case which only ever occurs
when path names without any directories are used from Python,
the overhead of expanding the working-directory for all data saving
operations isn't worthwhile.

The following changes have been made:

- bpy.ops.wm.save_mainfile() without a filepath argument
  fails & reports and error when the file hasn't been saved.

  Previously it would write to "untitled.blend" and set the
  `G.main->filepath` to this as well.

- bpy.ops.wm.save_mainfile(filepath="untitled.blend")
  fails & reports and error as the filename has no directory component.

- `BLI_path_is_abs_from_cwd` was added to check if the path would
  attempt to expand to the CWD.
---
 source/blender/blenlib/BLI_path_util.h    |  8 +++++++-
 source/blender/blenlib/intern/path_util.c | 30 ++++++++++++++++++------------
 2 files changed, 25 insertions(+), 13 deletions(-)

(limited to 'source/blender/blenlib')

diff --git a/source/blender/blenlib/BLI_path_util.h b/source/blender/blenlib/BLI_path_util.h
index 9e2970f6013..3cffecae187 100644
--- a/source/blender/blenlib/BLI_path_util.h
+++ b/source/blender/blenlib/BLI_path_util.h
@@ -323,9 +323,15 @@ void BLI_path_frame_strip(char *path, char *ext) ATTR_NONNULL();
  * Check if we have '#' chars, usable for #BLI_path_frame, #BLI_path_frame_range
  */
 bool BLI_path_frame_check_chars(const char *path) ATTR_NONNULL();
+/**
+ * Checks for a relative path (ignoring Blender's "//") prefix
+ * (unlike `!BLI_path_is_rel(path)`).
+ * When false, #BLI_path_abs_from_cwd would expand the absolute path.
+ */
+bool BLI_path_is_abs_from_cwd(const char *path) ATTR_NONNULL();
 /**
  * Checks for relative path, expanding them relative to the current working directory.
- * Returns true if the expansion was performed.
+ * \returns true if the expansion was performed.
  *
  * \note Should only be called with command line paths.
  * This is _not_ something Blender's internal paths support, instead they use the "//" prefix.
diff --git a/source/blender/blenlib/intern/path_util.c b/source/blender/blenlib/intern/path_util.c
index c40eed711f5..de71188abfe 100644
--- a/source/blender/blenlib/intern/path_util.c
+++ b/source/blender/blenlib/intern/path_util.c
@@ -1002,25 +1002,30 @@ bool BLI_path_abs(char *path, const char *basepath)
   return wasrelative;
 }
 
-bool BLI_path_abs_from_cwd(char *path, const size_t maxlen)
+bool BLI_path_is_abs_from_cwd(const char *path)
 {
-#ifdef DEBUG_STRSIZE
-  memset(path, 0xff, sizeof(*path) * maxlen);
-#endif
-  bool wasrelative = true;
-  const int filelen = strlen(path);
+  bool is_abs = false;
+  const int path_len_clamp = BLI_strnlen(path, 3);
 
 #ifdef WIN32
-  if ((filelen >= 3 && BLI_path_is_abs(path)) || BLI_path_is_unc(path)) {
-    wasrelative = false;
+  if ((ppath_len_clamp >= 3 && BLI_path_is_abs(path)) || BLI_path_is_unc(path)) {
+    is_abs = true;
   }
 #else
-  if (filelen >= 2 && path[0] == '/') {
-    wasrelative = false;
+  if (path_len_clamp >= 2 && path[0] == '/') {
+    is_abs = true;
   }
 #endif
+  return is_abs;
+}
 
-  if (wasrelative) {
+bool BLI_path_abs_from_cwd(char *path, const size_t maxlen)
+{
+#ifdef DEBUG_STRSIZE
+  memset(path, 0xff, sizeof(*path) * maxlen);
+#endif
+
+  if (!BLI_path_is_abs_from_cwd(path)) {
     char cwd[FILE_MAX];
     /* in case the full path to the blend isn't used */
     if (BLI_current_working_dir(cwd, sizeof(cwd))) {
@@ -1031,9 +1036,10 @@ bool BLI_path_abs_from_cwd(char *path, const size_t maxlen)
     else {
       printf("Could not get the current working directory - $PWD for an unknown reason.\n");
     }
+    return true;
   }
 
-  return wasrelative;
+  return false;
 }
 
 #ifdef _WIN32
-- 
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